package com.sinosoft.utils.encrypt;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import javax.crypto.spec.IvParameterSpec;
import java.nio.charset.Charset;
import java.util.UUID;

/**<pre>
 * 加密
 *   DES2Util des = new DES2Util(UUID.randomUUID().toString());//自定义密钥
	   System.out.println("加密前的字符："+test);
	   System.out.println("加密后的字符："+des.encrypt(test));
	   System.out.println("解密后的字符："+des.decrypt(des.encrypt(test)));
	   </pre>
 */
public class DES2Util {
	private static String strDefaultKey = "national";
	private Charset charset = Charset.forName("utf-8");
	private Cipher encryptCipher = null;
	private Cipher decryptCipher = null;
	
	/**
	 * 将byte数组转换为表示16进制值的字符串， 如：byte[]{8,18}转换为：0813， 和public static byte[]
	 * hexStr2ByteArr(String strIn) 互为可逆的转换过程
	 * 
	 * @param arrB
	 *            需要转换的byte数组
	 * @return 转换后的字符串
	 * @throws Exception
	 *             本方法不处理任何异常，所有异常全部抛出
	 */
	public static String byteArr2HexStr(byte[] arrB) throws Exception {
		int iLen = arrB.length;
		// 每个byte用两个字符才能表示，所以字符串的长度是数组长度的两倍
		StringBuffer sb = new StringBuffer(iLen * 2);
		for (int i = 0; i < iLen; i++) {
			int intTmp = arrB[i];
			// 把负数转换为正数
			while (intTmp < 0) {
				intTmp = intTmp + 256;
			}
			// 小于0F的数需要在前面补0
			if (intTmp < 16) {
				sb.append("0");
			}
			sb.append(Integer.toString(intTmp, 16));
		}
		return sb.toString();
	}

	/**
	 * 将表示16进制值的字符串转换为byte数组， 和public static String byteArr2HexStr(byte[] arrB)
	 * 互为可逆的转换过程
	 * 
	 * @param strIn
	 *            需要转换的字符串
	 * @return 转换后的byte数组
	 * @throws Exception
	 *             本方法不处理任何异常，所有异常全部抛出
	 */
	public static byte[] hexStr2ByteArr(String strIn) throws Exception {
		byte[] arrB = strIn.getBytes();
		int iLen = arrB.length;

		// 两个字符表示一个字节，所以字节数组长度是字符串长度除以2
		byte[] arrOut = new byte[iLen / 2];
		for (int i = 0; i < iLen; i = i + 2) {
			String strTmp = new String(arrB, i, 2);
			arrOut[i / 2] = (byte) Integer.parseInt(strTmp, 16);
		}
		return arrOut;
	}

	/**
	 * 默认构造方法，使用默认密钥
	 * 
	 * @throws Exception
	 */
	public DES2Util() throws Exception {
		this(strDefaultKey);
	}

	/**
	 * 指定密钥构造方法
	 * 
	 * @param strKey
	 *            指定的密钥
	 * @throws Exception
	 */
	public DES2Util(String strKey)   {
		try {
			byte[] keysBytes = this.getKey(strKey.getBytes(charset));
			
	        DESKeySpec desKeySpec = new DESKeySpec(keysBytes);
	        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
	        SecretKey secretKey = keyFactory.generateSecret(desKeySpec);
	        IvParameterSpec iv = new IvParameterSpec(keysBytes);
			
	        encryptCipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
	        encryptCipher.init(Cipher.ENCRYPT_MODE, secretKey, iv);
	        
	        decryptCipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
	        decryptCipher.init(Cipher.DECRYPT_MODE, secretKey, iv);
	        
			
		} catch (Exception e) {
			throw new RuntimeException(e);
		} 
	}

	/**
	 * 加密字节数组
	 * 
	 * @param arrB
	 *            需加密的字节数组
	 * @return 加密后的字节数组
	 * @throws Exception
	 */
	public byte[] encrypt(byte[] arrB)   {
		try {
			return encryptCipher.doFinal(arrB);
		}  catch (Exception e) {
			throw new RuntimeException(e);
		} 
	}

	/**
	 * 加密字符串
	 * 
	 * @param strIn
	 *            需加密的字符串
	 * @return 加密后的字符串
	 * @throws Exception
	 */
	public String encrypt(String strIn) {
		String re = null;
		try {
			re =  byteArr2HexStr(encrypt(strIn.getBytes()));
		} catch (Exception e) {
			re = strIn;
			e.printStackTrace();
		}
		return re;
	}

	/**
	 * 解密字节数组
	 * 
	 * @param arrB
	 *            需解密的字节数组
	 * @return 解密后的字节数组
	 * @throws Exception
	 */
	public byte[] decrypt(byte[] arrB)   {
		try {
			return decryptCipher.doFinal(arrB);
		}  catch (Exception e) {
			throw new RuntimeException(e);
		} 
	}

	/**
	 * 解密字符串
	 * 
	 * @param strIn
	 *            需解密的字符串
	 * @return 解密后的字符串
	 * @throws Exception
	 */
	public String decrypt(String strIn)   {
		String re = null;
		try {
			re =  new String(decrypt(hexStr2ByteArr(strIn)));
		} catch (Exception e) {
			re= strIn;
			e.printStackTrace();
		} 
		return re;
	}

	/**
	 * 从指定字符串生成密钥，密钥所需的字节数组长度为8位 不足8位时后面补0，超出8位只取前8位
	 * 
	 * @param arrBTmp
	 *            构成该字符串的字节数组
	 * @return 生成的密钥
	 * @throws Exception
	 */
	private byte[] getKey(byte[] arrBTmp) throws Exception {
		// 创建一个空的8位字节数组（默认值为0）
		byte[] arrB = new byte[8];
		// 将原始字节数组转换为8位
		for (int i = 0; i < arrBTmp.length && i < arrB.length; i++) {
			arrB[i] = arrBTmp[i];
		}
		return arrB;
	}
	 /**
	  * @param args
	  */
	 public static void main(String[] args) {
	  // TODO Auto-generated method stub
	  try {
	   String test = "asdfasdfadsf";
	   //CryptTest des = new CryptTest();//默认密钥
	   DES2Util des = new DES2Util(UUID.randomUUID().toString());//自定义密钥
	   System.out.println("加密前的字符："+test);
	   System.out.println("加密后的字符："+des.encrypt(test));
	   System.out.println("解密后的字符："+des.decrypt(des.encrypt(test)));
	  } catch (Exception e) {
	   // TODO: handle exception
	   e.printStackTrace();
	  }
	 }

}